Synopsis On 06 April 1993, the Canadian self-unloading bulk carrier HALIFAX was transiting St. Mary's River, Ontario. Repairs to the unloading system were near completion and the hydraulic system was being tested by the three tunnelmen, when a major fire broke out in the centre tunnel below the cargo holds. A hose to a gate valve was found disconnected after the fire. The fire was successfully extinguished by the crew, but the head tunnelman lost his life. The Board determined that the fire broke out in the conveyor belt tunnel aboard the HALIFAX when the hydraulic oil mist from the disconnected hose was ignited by a halogen lamp that was missing a protective lens cover. 1.0 Factual Information 1.1 Particulars of the Vessel HALIFAX Port of Registry - Toronto, Ontario Flag - Canadian Official Number - 313963 Type - Great Lakes self-unloading bulk carrier Built - 1963, Lauzon, Quebec Gross Tons - 20,646 Length - 222.56 m Draught max. F2: 4.87 m - a: 7.01 m Propulsion - Two steam turbine engines, 7,356 kW, 17 knots (kn) Owners - Canada Steamship Lines Inc. Montreal, Quebec 1.1.1 Description of the Vessel The HALIFAX has the navigation bridge and associated accommodation located forward, and an engine-room and the balance of the accommodation located aft. The 6 cargo holds are served by 17 hatches that are separated by 7 structural but non-watertight transverse bulkheads. The vessel is equipped with two cargo-unloading conveyor belts arranged longitudinally in a hopper-topped tunnel under cargo holds. (For a typical midship cross-section see Appendix A.) A transfer... 1 Units of measurement in this report conform to International Maritime Organization (IMO) standards or, where there is no such standard, are expressed in the International System (SI) of units. 2 See Glossary for all abbreviations and acronyms. ...and loop belt conveyor system, located at the after end of the tunnel in a vertical casing on the ship's centre line, serves a swivelling unloading conveyor boom at the main-deck level. Below the hopper is the tunnel which can be accessed from either forward or aft. The hopper gates and the vibrators are operated by a hydraulic system. The gates feed the cargo on to the conveyor belt, and the vibrators, which are mounted on the saddleback, help to loosen the cargo stuck to it. Manually operated spool valves are used to isolate hydraulics to each component. Where necessary, some spool valves are fitted with two independently operated control handles, one to operate the gates and the other to operate the vibrator. The pumps for the system are located on the main deck at the forward end of the aft accommodation. 1.1.2 Tunnel Illumination In addition to the permanent lighting in the tunnel, portable lighting comprising a cargo cluster light and a halogen lamp (see Appendix B, Figure 1) were used to better illuminate the large work area. The halogen lamp was positioned approximately 0.6 m off the deck on the conveyor belt framing facing the gate some 1.5 m aft of the No. 4 gate valve. 1.2 Chronology of Events On 06 April 1993, the HALIFAX, while en route from Nanticoke, Ontario, to Duluth, Minnesota, was in ballast and approaching Sault Ste. Marie Locks, Michigan, United States of America (USA). As the hydraulically operated No. 4 hopper gate (near frames 42-44) at the after end of the No. 1 hold was not opening, the head tunnelman, tunnelman No. 1 and tunnelman No. 2, had been working on the system for two days. The repairs comprised replacement of the No. 4 gate valve and then of one of the actuating cylinders. The removal of the cylinder required the heating of one of its retaining pins with an oxyacetylene torch. After the work had been completed, the valves at the torch were shut off, leaving the valves at the cylinders open, and the torch was left in the starboard tunnel (see Appendix B, Figure 1). In the interim, one acetylene cylinder was changed late in the morning. At about 13553, the area was hosed down with water. At approximately 1416, under instructions from the head tunnelman, tunnelman No. 2 proceeded to the main deck, a distance of about 140 to 150 m, to activate the hydraulic pumps. In preparation for the hydraulic test, the head tunnelman was positioned in the vicinity of the No. 4 gate valve in the centre tunnel while tunnelman No. 1 was positioned near the No. 4 cylinder in the starboard tunnel. After activating two of the three hydraulic pumps, tunnelman No. 2 returned to the tunnel. 3 All times are expressed in EST (Coordinated Universal Time (UTC) minus five hours) unless otherwise stated. Meanwhile at about 1419, in response to the queries from the head tunnelman, tunnelman No. 1 indicated that the cylinder had not moved. The two men were some 3 to 5 m away from each other with considerable equipment between them, such that their legs were barely visible to the other person. At this time, there was no detectable smell of acetylene. Tunnelman No. 1 reportedly heard a noise that sounded similar to a vibrator being activated but not as loud, followed, within a couple of seconds, by a large orange flame and then black smoke. He then exited by way of the forward tunnel exit. By the time he reached the forward end of the tunnel (which took some 12 to 15 seconds), he was inhaling thick black smoke. When tunnelman No. 2 was some 20 to 25 m from the work area in the centre tunnel, he saw a flame, which he associated with some further burning by the head tunnelman, in the vicinity of the starboard belt and not near the oxyacetylene bottles. The bottles were positioned between frames 42 and 43 on the port side of the centre tunnel with the hoses running under the conveyor belt, and the torch was located in the starboard tunnel. Tunnelman No. 2 then observed a big burst of flame and associated this with burning oil. Immediately thereafter, he saw a fire-ball that appeared to be moving forward. This was followed rapidly by thick black smoke. He then ran aft and proceeded to shut down the hydraulic pumps; an estimated two to three minutes had elapsed between the time the pumps were started and the outbreak of fire. Upon reaching the main deck, tunnelman No. 1 activated the fire alarm which was followed, a minute later, by the master sounding the general alarm. A count of the crew indicated that the head tunnelman was missing. While the crew attempted to fight the fire, the master contacted the American authorities for assistance. The vessel was granted permission to proceed at full speed. With the assistance of a US tug and two private tugs, the vessel eventually berthed at the Old Carbide dock in Sault Ste. Marie (SSM), Michigan. By the time the vessel berthed, the fire, which had been brought under control, was almost extinguished. 1.3 Weather Information The weather was fine and clear with wind from the east at 10 to 15 kn, and the air temperature was 9C. 1.4 Injuries to Persons Of the three persons in the tunnel, one suffered minor smoke inhalation and the head tunnelman lost his life as a result of asphyxiation and extensive burns. The autopsy revealed that the victim had second- and third-degree burns to the trunk, abdomen and upper legs, and first- to second-degree burns to the back, but there were no burns on the lower legs below mid-calf. The pattern of burns suggests the possibility of flammable materials being released at the time of the accident which may have saturated the clothing. It also suggests possible loss of consciousness associated with head trauma. Toxicology tests found the carbon monoxide level in the blood to be 37.9 per cent. At the time the victim's body was retrieved, it was observed that the head tunnelman was burned more severely on the right side. Studies show that carbon monoxide levels in blood between 30 and 40 per cent generally result in disturbance in judgement and possible confusion. 1.4.1 Position of Body The head tunnelman's body was found approximately 8 m forward of the work area. The body was forward of the oxyacetylene cylinders, to the port side of the centre tunnel, between support pillars. He was lying with his head aft and feet forward in a semi-fetal position. Burnt clothing was found 0.4 m off the deck on the two pillars nearest the body. His rubber boots were off and lying some metres symmetrically beyond his head. 1.5 Fire Damage Examination of the fire area revealed the following: The most intense fire-damaged area was in the forward section of the tunnel on the starboard side of the centre tunnel at the after end of the No. 4 hopper under the No. 1 hold. Vertical frames 46 and 49 were warped due to heat, and some 35 m of the rubber conveyor belt had been consumed. Metal bulkheads and the metal tray holding the electrical wires were distorted by heat. The aluminium end housing of the vibrator, which was aft of the No. 4 gate hydraulic controls, had melted away and a large molten glob remained on the deck. All wiring showed external heat and fire damage. Overall heat and smoke damage extended to the after end of the No. 3 hold. Smoke damage throughout the forward accommodation in varying degrees, the worst being near ventilation louvres. Previously discontinued hydraulic lines and fittings were scorched within the immediate area of the fire and were hanging askew. The regulators on the oxygen and acetylene bottles were partially melted and burned by the fire. 1.6 Vessel and Personnel Certification The vessel was manned, equipped and certificated in accordance with existing regulations. Recognizing a shortfall in the compliance with the Fire Detection and Extinguishing Regulations in the tunnel space aboard self-unloading bulk carriers, the Ship Safety Branch of the Canadian Coast Guard (CCG) issued a letter dated 04 February 1985. The letter reminded all ship safety surveyors in the Central and Laurentian regions to ensure that the fire hydrants and hoses in the tunnel space were in compliance with the regulatory requirements. It further stated that any shortfall should immediately be brought to the attention of the owners who should correct it as soon as possible, and the Regional Headquarters should also be notified. On 25 March 1992, some seven years later, the HALIFAX was issued a SI-7 requiring that hoses and hydrants of regulatory size be fitted in the tunnel to conform with Section 61(1) of the Fire Detection and Extinguishing Regulations. Following another survey, the vessel was issued a Cargo Ship Safety Equipment Certificate on 28 March 1993 without the shortfalls contained in the 1992 SI-7 having been remedied. Until the time of the occurrence, the owners had not rectified the hose and hydrant in the tunnel to meet the requirements. 1.6.1 Personnel History All tunnelmen had attended a Marine Emergency Duties (MED) course and a company- sponsored welding course highlighting work safety in the tunnel spaces. They had also attended a basic Hydraulic Operations course co-sponsored by the union and the company. The courses also highlighted safe working practices associated with maintenance on self-unloading bulkers. The head tunnelman had served as a tunnelman, in junior and senior capacities, for the past 19 years. He was described as a patient, private individual who took pride in his work and had been commended several times on his performance. Tunnelman No. 1 and tunnelman No. 2 each had some 10 years' experience working in that position with the head tunnelman. Tunnelman No. 2 had some 23 years of tunnel-work experience. 1.7 Hydraulic System The three hydraulic pumps are rated at 3.78 L/sec and typically operate at 5,500 kPa (800 psi) with a maximum pressure of 8,270 kPa (1,200 psi). Inspection of the reservoir revealed that the fluid was down about 15 cm indicating that some 400 to 450 L of fluid had been dispensed. The Parker hydraulic hose in use was suitable for petroleum-based hydraulic fluids and had a minimum working pressure of 13,780 kPa (2,000 psi) with a minimum burst pressure of 55,120 kPa (8,000 psi). There was no evidence to indicate that the hydraulic hose had burst. Photographic evidence of the fire site shows that the hydraulic hose from the main hydraulic line to the input of the No. 4 gate valve was found disconnected after the fire (see Appendix C, Figure 1), and there was no evidence of damage to the threads (see Appendix C, Figure 2). 1.7.1 Hydraulic System Tests After the No. 4 cylinder was replaced, two tests were conducted on the hydraulic system. During the first test, there was good pressure at the vibrator end, and while the vibrator was functional, the gate was not. The system was then shut down. After being re-examined, the No. 4 cylinder was being tested for the second time when fire broke out in the conveyor belt tunnel. 1.8 Characteristics of Hydraulic Fluid in Use The hydraulic fluid in use was Esso UNIVIS N-22. According to the UNIVIS product data sheet, the oil has a flashpoint of 155C. The upper and lower flammable limits of hydraulic oil vary slightly depending on the chemical composition of the oil. A typical hydraulic oil has flammable limits of between 2.5 and 6 per cent. Tests conducted by the National Research Council (NRC) on the sample of used oil from the vessel indicated that the flashpoint and fire point were 174C and 184C, respectively. For new oil, these figures were 179C and 185C respectively. In this occurrence, the flammability of hydraulic oil in mist form in the presence of a high-intensity halogen lamp was not fully appreciated in terms of the heat generated by the lamp and of the auto-ignition temperature of the hydraulic oil. 1.9 Properties of Acetylene Gas According to the Canadian Centre for Occupational Health and Safety, acetylene is a flammable, colourless gas with no or slight garlic-like odour dependent on purity. It warns that one should not draw conclusions based on odour observations alone. However, acetylene of ordinary commercial purity generated from calcium carbide has a distinctive garlic-like odour. Acetylene is slightly lighter than air; relative density compared to air is 0.9. The lower explosive limit (LEL) is 2.5 per cent and the upper explosive limit (UEL) is 81 per cent. The flashpoint of acetylene is - 18C and the auto-ignition temperature is 305C. 1.10 Halogen Lamp According to the manufacturer, the type of halogen lamp in use was Canadian Standards Association (CSA) certified for use in outdoor locations. A typical lamp fixture comprises a cast aluminium body which is designed with a specialized heat-dissipating fin system for cooler operation. A parabolic reflector system provides maximum light output and control. The thermal-shock- and impact-resistant glass lens is mounted in a die cast aluminium door frame. A weathertight seal is provided by a high-temperature silicon door gasket, and stainless steel eccentric latches ensure consistent lens pressure. The halogen lamp was mounted on a steel bracket with an electrical junction box attached to the rear of the bracket and an extension cord hardwired into the junction box (see Appendix C, Figures 3A and 3B). In this instance, the halogen lamp fixture in use did not have the protective lens in place. 1.10.1 Halogen Lamp and Ignition Tests Tests conducted on the halogen lamp recorded surface temperatures in excess of 600C at the lamp, decreasing to approximately 350C five centimetres from the lamp surface. Considerable smoke was generated when UNIVIS N-22 hydraulic oil was added directly to the illuminated light, but ignition did not take place. In a second test, when a mist of UNIVIS N-22 oil was sprayed through a flame source, a substantial fire-ball was produced. 1.10.2 Ship's Electrical Standards The electrical system and appliances used aboard a Canadian vessel are governed by the CCG Ship's Electrical Standards. Section 18(4) states that the temperature of those parts of the lighting fixtures that can be handled by any individual shall not exceed 60C. In this instance, tests with the lens cover in place also showed that the lens cover reached a steady state temperature of 270C. 1.11 Presence of Accelerant in the Tunnel At the time of the fire, one full oxygen and two acetylene cylinders, one empty and the other nearly full, were present on the port side of the centre tunnel (Appendix B, Figure 1). One acetylene tank had been changed that morning. With the onset of the fire and with the oxyacetylene cylinder valves open and the hoses burnt, intense fire and heat were generated by the introduction of these flammable materials; the effects of which could be felt on the bridge of the vessel. There was no evidence to suggest explosion within the tunnel due to the presence of acetylene. 1.12 Oxyacetylene Cylinders The carriage of dangerous goods such as acetylene is governed by the Transportation of Dangerous Goods Regulations made pursuant to the Dangerous Goods Act. Part VI of the regulations states that: No person shall handle or offer for the transport of a cylinder ... containing dangerous goods ... unless the National Standards of Canada ... are complied with. The Canadian National Standards (CAN/CSA B340-M88 and CAN/CSA B339-88) require all acetylene cylinders to be fitted with a fusible plug. The fusible plug is intended to prevent explosion of acetylene bottles exposed to fire and is constructed of metal which will melt at a temperature of about 68C. According to the regulatory agency, the CCG, as the oxyacetylene cylinders were part of the ship's stores, they were not required to comply with either the aforementioned regulations or standards. The two acetylene bottles in the tunnel were not built to Canadian National Standards. The valve of the acetylene cylinder in use was not closed. Since the oxyacetylene cylinder valves were left open, the burnt hoses allowed gases to burn in a controlled manner. Thus, inadvertently, the act of keeping the oxyacetylene valves open effectively served the function of a fusible plug. The post-fire inspection and/or testing of the oxyacetylene equipment in use revealed the following: There was a negligible quantity of oxygen and acetylene in the bottles. The handle of the oxygen shut-off valve was partially melted. The regulator gauges attached to the oxyacetylene cylinders were both partially melted (see Appendix C, Figure 4). The regulator fittings had tapered threads and the cylinder valve had straight threads requiring the use of an adapter. The hoses originally attached to the regulator were burned off with about 8 m remaining attached to the torch; the torch was located in the starboard tunnel (Appendix C, Figure 5). There were no flashback arresters installed on the regulators nor are any required by regulations. The knob of the oxygen shut-off valve on the torch was missing and the valve stem was bent requiring a tool to turn the valve stem, but the tests showed the valve to be functioning satisfactorily. The acetylene valve on the torch was complete, the valve was closed and operated normally. The hose connections at the torch were tight and the tip nut was seated properly and in good condition. The hose connections at the torch did not have non-return valves installed nor are any required by regulations. The remaining hose, which had been in service for approximately two years, was in relatively good condition with no splices or crazing of the hose. 1.13 TSB Engineering Report The TSB Engineering Branch report based on the examination and testing of material present at the fire site and other available information concluded, among others, the following: The hydraulic hose normally attached to the input of the No. 4 hopper gate valve was, or became, disconnected from the valve for undetermined reasons. The pressurizing of the hydraulic system allowed hydraulic oil to be sprayed from the disconnected hose, forming a flammable mist. The protective lens cover on the quartz halogen lamp in use was missing. The UNIVIS N-22 in a mist form could have ignited when it came in contact with the exposed illuminated quartz halogen lamp. 1.14 Other Considerations The TSB Engineering Branch report also determined that the conveyor belt involved in the fire was not a primary source of fuel in this case. It was also determined that the oxyacetylene torch, the electrical extension cord, the electrical equipment and the other area lighting were not the source of ignition for the hydraulic oil. 1.15 Fire-fighting Equipment in the Tunnel The vessel was required to carry fire-fighting equipment in accordance with existing regulations. The equipment on board included a fire main comprising a 51 mm line with fire hoses positioned at various locations within the vessel, fire extinguishers, breathing apparatus and a fireman's outfit. However, the hydrants and hoses in the tunnel, primarily intended for hosing down, were not of regulatory size nor were the hoses manufactured of material approved for a fire-fighting hose; the fire extinguishers were suitably located. The fire was successfully extinguished by personnel wearing breathing apparatus and fire suits using fire hoses, and the point of entry to the tunnel was from the forward end by way of the laundry area. 1.16 Fire-fighting Most of the fire-fighting effort was conducted by the ship's crew assisted toward the end by the SSM, Michigan, Fire Department and the United States Coast Guard (USCG) with the Canadian Sault Ste. Marie Fire Department standing by. At approximately 1425, the fire-fighting party, under the direction of the first mate, donned air packs. In the initial stages, two attempts were made to reach the fire site from the laundry room, but they were unsuccessful due to intense heat. Nos. 1 and 2 hatches were then opened and three hoses were directed at the starboard cargo gates and the saddleback at about 1444. Tunnel fans were not used for fear of feeding the fire with oxygen. The deluge sprinkling system in the loop belt casing area aft was turned on to inundate the fire with water and to cool the belt. Difficulties were experienced in handling the long lengths of five hoses around corners and obstacles. When the last air bottle had been half-consumed, the first mate informed the master to request back-up. The crew of the USCG vessel KATMAI BAY, equipped with fire- fighting gear, boarded the HALIFAX and provided general assistance. The third mate took charge of the team on deck. By the time the fire chief from SSM boarded the HALIFAX, the fire had been brought under control. Shortly thereafter, the chief mate and the fire chief recovered the body of the head tunnelman with assistance from another seaman, at about 1506. In the fire-fighting effort, a total of 14 air bottles had been used. 1.17 Fire Precautions The Safe Working Practices Regulations made pursuant to the Canada Shipping Act and the Canada Labour Code both require sufficient fire extinguishers to be placed in the vicinity where hot work operations are carried out. In this instance, a fire extinguisher was kept at hand. 1.18 Clothing Worn by Tunnelman The victim, the head tunnelman, wore rubber boots and coveralls made with a material of 65 per cent polyester and 35 per cent cotton. In this instance, the hydraulic oil in conjunction with the soot associated with the fire smoke would have accelerated the burning rate. Tests conducted show that pure untreated cotton is more fire-resistant than a blend using any percentage of polyester. 1.19 Work Practices and Safety The chief engineer, as head of the engineering department, was responsible for the maintenance of equipment in the tunnel. Periodically, checks would be carried out to monitor the progress of the repairs. The impact of some work practices employed on board the vessel, as reflected in the occurrence, were not fully appreciated and included the following: Use of a longer length of flexible hydraulic hose than required to carry out repairs. Slacking back of the hydraulic hose connection to check for fluid flow while the system was under pressure. Use of a high-intensity lighting fixture, that is intended for outdoor use, in confined spaces; a practice in recent use. Practice of keeping the oxygen and acetylene cylinder valves open when the equipment was not in use.